Quantum reactive scattering of ultracold NH($X\,^3\Sigma^-$) radicals in a magnetic trap

TL;DR

This study uses quantum scattering calculations to analyze ultracold NH radical reactions in a magnetic trap, revealing non-universal behavior and implications for molecular cooling.

Contribution

It provides the first detailed quantum mechanical analysis of NH + NH reactions at ultracold temperatures, highlighting non-universality and reaction-driven trap loss.

Findings

Reactive cross section is weakly dependent on magnetic field.

NH + NH scattering is non-universal.

Chemical reactions cause significant trap loss.

Abstract

We investigate the ultracold reaction dynamics of magnetically trapped NH($X ^3\Sigma^-$) radicals using rigorous quantum scattering calculations involving three coupled potential energy surfaces. We find that the reactive NH + NH cross section is driven by a short-ranged collisional mechanism, and its magnitude is only weakly dependent on magnetic field strength. Unlike most ultracold reactions observed so far, the NH + NH scattering dynamics is non-universal. Our results indicate that chemical reactions can cause more trap loss than spin-inelastic NH + NH collisions, making molecular evaporative cooling more difficult than previously anticipated.